Paul Roekaerts

Infusion of propofol versus midazolam for sedation in the intensive care unit following coronary artery surgery

The use and the hemodynamic effects of propofol and midazolam were studied during titrated continuous infusions to deep sedation (sedation level 5: asleep, sluggish response to light glabellar tap or loud auditory stimulus) following coronary artery surgery. The drugs were compared in 30 ventilated patients in an open randomized study. The duration of infusion was approximately 570 minutes in both groups. After a loading dose of propofol (1 mg/kg) or midazolam (0.07 mg/kg), the infusion rates were 2.71 +/- 1.13 mg/kg/h and 0.092 +/- 0.028 mg/kg/h, respectively. An analgesic infusion of sufentanil was also given in both groups. In the midazolam group, to maintain the predetermined level of sedation, more frequent additional bolus doses (4.7 +/- 1.8; P < 0.001) and infusion rate adjustments (5.3 +/- 1.6; P < 0.001) were required than for similar sedation in the propofol group (2.3 +/- 1.0 bolus doses and 3.3 +/- 1.2 adjustments). The time from stopping sedation to patient responsiveness was 11 +/- 8 minutes in the propofol group and 72 +/- 70 minutes in the midazolam group (P < 0.001), and the time from stopping sedation to extubation was 250 +/- 135 minutes and 391 +/- 128 minutes (P < 0.014), respectively. Following the loading dose of propofol, there was a fall in blood pressure (BP) (mean from 80 +/- 11 mmHg to 67.5 +/- 10 mmHg; P < 0.05). After approximately 15 minutes, BP started to rise but remained below pretreatment level throughout sedation.(ABSTRACT TRUNCATED AT 250 WORDS)

Impaired Skeletal Muscle Substrate Oxidation in Glucose-intolerant Men Improves After Weight Loss

Objective: An impaired fatty acid handling in skeletal muscle may be involved in the development of insulin resistance and diabetes mellitus type 2 (DM2). We investigated muscle fatty acid metabolism in glucose‐intolerant men (impaired glucose tolerance (IGT)), a prediabetic state, relative to BMI‐matched control men (normal glucose tolerance (NGT)) during fasting and after a meal, because most people in the western society are in the fed state most of the day.

Analysis of volatile organic compounds in exhaled breath to diagnose ventilator-associated pneumonia

Ventilator-associated pneumonia (VAP) is a nosocomial infection occurring in the intensive care unit (ICU). The diagnostic standard is based on clinical criteria and bronchoalveolar lavage (BAL). Exhaled breath analysis is a promising non-invasive method for rapid diagnosis of diseases and contains volatile organic compounds (VOCs) that can differentiate diseased from healthy individuals. The aim of this study was to determine whether analysis of VOCs in exhaled breath can be used as a non-invasive monitoring tool for VAP. One hundred critically ill patients with clinical suspicion of VAP underwent BAL. Before BAL, exhaled air samples were collected and analysed by gas chromatography time-of-flight mass spectrometry (GC-tof-MS). The clinical suspicion of VAP was confirmed by BAL diagnostic criteria in 32 patients [VAP(+)] and rejected in 68 patients [VAP(−)]. Multivariate statistical comparison of VOC profiles between VAP(+) and VAP(−) revealed a subset of 12 VOCs that correctly discriminated between those two patient groups with a sensitivity and specificity of 75.8% ± 13.5% and 73.0% ± 11.8%, respectively. These results suggest that detection of VAP in ICU patients is possible by examining exhaled breath, enabling a simple, safe and non-invasive approach that could diminish diagnostic burden of VAP.

Electronic nose analysis of exhaled breath to diagnose ventilator-associated pneumonia.

BACKGROUND Exhaled breath analysis is an emerging technology in respiratory disease and infection. Electronic nose devices (e-nose) are small and portable with a potential for point of care application. Ventilator-associated pneumonia (VAP) is a common nosocomial infection occurring in the intensive care unit (ICU). The current best diagnostic approach is based on clinical criteria combined with bronchoalveolar lavage (BAL) and subsequent bacterial culture analysis. BAL is invasive, laborious and time consuming. Exhaled breath analysis by e-nose is non-invasive, easy to perform and could reduce diagnostic time. Aim of this study was to explore whether an e-nose can be used as a non-invasive in vivo diagnostic tool for VAP. METHODS Seventy-two patients met the clinical diagnostic criteria of VAP and underwent BAL. In thirty-three patients BAL analysis confirmed the diagnosis of VAP [BAL+(VAP+)], in thirty-nine patients the diagnosis was rejected [BAL-]. Before BAL was performed, exhaled breath was sampled from the expiratory limb of the ventilator into sterile Tedlar bags and subsequently analysed by an e-nose with metal oxide sensors (DiagNose, C-it, Zutphen, The Netherlands). From further fifty-three patients without clinical suspicion of VAP or signs of respiratory disease exhaled breath was collected to serve as a control group [control(VAP-]). The e-nose data from exhaled breath were analysed using logistic regression. RESULTS The ROC curve comparing [BAL+(VAP+)] and [control(VAP-)] patients had an area under the curve (AUC) of 0.82 (95% CI 0.73-0.9). The sensitivity was 88% with a specificity of 66%. The comparison of [BAL+(VAP+)] and [BAL-] patients revealed an AUC of 0.69; 95% CI 0.57-0.81) with a sensitivity of 76% with a specificity of 56%. CONCLUSION E-nose lacked sensitivity and specificity in the diagnosis of VAP in the present study for current clinical application. Further investigation into this field is warranted to explore the diagnostic possibilities of this promising new technique.

Cardiac Output Measurement by Bioimpedance and Noninvasive Pulse Contour Analysis Compared With the Continuous Pulmonary Artery Thermodilution Technique

OBJECTIVE The aim of the present study was to compare 2 noninvasive cardiac output measurement methods with the continuous cardiac output thermodilution (CCO-TD) method. DESIGN A single-center prospective design. SETTING A university hospital. PARTICIPANTS Fifty-three consecutive patients scheduled for elective, non-emergent cardiac surgery. INTERVENTIONS With each participant the cardiac output was measured using 3 methods: CCO-TD, the Endotracheal Cardiac Output Monitor (ECOM), and the Nexfin monitor. MEASUREMENTS AND MAIN RESULTS Measurements were performed simultaneously at 7 time points: After induction, before cardiopulmonary bypass, after cardiopulmonary bypass, after protamine, after arrival in the intensive care unit, and before extubation on postoperative day 1. Statistical analysis was performed using Pearsons correlation, Bland-Altman, percent error, and polar plots. Compared to CCO-TD, ECOM showed significant correlation of R0.619 with a bias of -0.13 L/min (95% confidence interval -2.19-1.93 L/min), a percent error of 40%, and trending ability of 87% and 97% within 0.5 L/min and 1.0 L/min, respectively. The Nexfin monitor showed significant correlation of R0.535 with a bias of-0.35 L/min (95% confidence interval-3.36-2.66 L/min), a percent error of 58% and trending ability of 84% and 97% were within 0.5 L/min and 1.0 L/min limits of agreement. CONCLUSIONS Neither the ECOM nor the Nexfin had the ability to replace the thermodilution-based continuous cardiac output monitor. The ECOM did not have acceptable accuracy or trending ability and only could be utilized for intubated patients. The Nexfin lacked reliability and trending ability. Also, the Nexfin did not provide consistent results.

Coronary vascular effects of dexmedetomidine during reactive hyperemia in the anesthetized dog

OBJECTIVE The central sympatholytic effects of alpha2-adrenergic agonists are believed to be beneficial during myocardial ischemia, but the peripheral vasoconstrictive effects are controversial. The aim of this study was to investigate the coronary vascular effects of dexmedetomidine (DM) during reactive hyperemia. DESIGN The study had a prospective, randomized, open-comparative design. SETTING University animal laboratory. PARTICIPANTS Nine mongrel dogs. INTERVENTIONS Coronary artery occlusions lasting 2 minutes were induced five times at 40-minute intervals. DM, 0.1, 1, and 10 micrograms/kg was administered 15 minutes before the second, third, and fourth coronary occlusion, respectively. The alpha2-antagonist atipamezole was administered before the fifth coronary occlusion. MEASUREMENTS AND MAIN RESULTS DM, 1 microgram/kg, significantly decreased heart rate (from 128 +/- 13 to 96 +/- 21 beats/min); 10 micrograms/kg of DM also significantly decreased cardiac output (from 3.4 +/- 1.1 to 1.4 +/- 0.4 L/min). DM decreased myocardial blood flow in all layers of normally perfused myocardium. In hyperemic myocardium, DM significantly decreased epicardial blood flow (from 3.30 +/- 1.43 to 1.44 +/- 0.49 mL/min/g after DM 10 micrograms/kg), whereas endocardial blood flow did not change, hereby significantly increasing the endo/epi blood flow ratio (from 0.99 +/- 0.54 to 2.28 +/- 0.78). CONCLUSIONS In the postischemic hyperemic subendocardial layer, coronary blood flow was preserved after DM. DM reduced primary determinants of myocardial oxygen demand. These effects of DM may be beneficial in conditions of temporary coronary artery occlusion and subsequent reperfusion.

The effects of alpha 2-adrenergic stimulation with mivazerol on myocardial blood flow and function during coronary artery stenosis in anesthetized dogs.

The central sympatholytic effect of alpha2 agonists may be beneficial during myocardial ischemia, but could be opposed by their peripheral vasoconstrictive effect.We studied the effects of mivazerol during periods of moderate coronary artery stenosis in anesthetized dogs. Mivazerol decreased heart rate (from 125 +/- 6 to 106 +/- 6 bpm) and cardiac output (from 4.4 +/- 0.6 to 1.8 +/- 0.2 L/min) under normal conditions, while mean arterial pressure did not change. Mivazerol reduced blood flow in nonischemic myocardium and in the ischemic epicardial layer, but blood flow was preserved in the ischemic midmyocardial and subendocardial layer. Mivazerol had no effect on myocardial oxygen extraction during the stenoses, and regional myocardial oxygen consumption was unchanged. However, mivazerol decreased myocardial oxygen demand from 4.51 +/- 0.51 to 3.17 +/- 0.24 micro mol centered dot min-1 centered dot g-1, thereby reducing oxygen deficiency of ischemic myocardium to values significantly lower than in the placebo group (from 1.07 +/- 0.32 to 0.47 +/- 0.41 micro mol centered dot min-1 centered dot g-1). Mivazerol had no effect on myocardial lactate production during the stenoses. We conclude that mivazerol reduced myocardial oxygen demand while blood flow was preserved in the inner layers of ischemic myocardium. (Anesth Analg 1996;82:702-11)

Modalities and Effects of Left Ventricle Unloading on Extracorporeal Life support: a Review of the Current Literature

Veno‐arterial extracorporeal membrane oxygenation (V‐A ECMO) support is increasingly used in refractory cardiogenic shock and cardiac arrest, but is characterized by a rise in afterload of the left ventricle (LV) which may ultimately either further impair or delay cardiac contractility improvement. The aim of this study was to provide a comprehensive overview regarding the different LV venting techniques and results currently available in the literature.

Comparison of the effects of dexmedetomidine and esmolol on myocardial oxygen consumption in dogs

Background and objective: The beta-adrenergic blocker esmolol and the alpha 2-adrenergic agonist dexmedetomidine have the potential to decrease perioperative myocardial ischaemia. The pathophysiological mechanisms involved in these anti-ischaemic properties have not been thoroughly studied. We compared the effects of esmolol and dexmedetomidine on two indices of overall myocardial oxygen demand and on directly measured myocardial oxygen consumption of the left anterior coronary artery territory. Methods: Eleven mongrel dogs were instrumented to measure aortic and left ventricular pressure, aortic and left anterior coronary artery flow and myocardial wall thickening. Variables related to myocardial oxygen metabolism were also determined. Measurements were performed during four sequential experimental conditions in each dog (Control 1: esmolol; Control 2: dexmedetomidine). Results: Esmolol and dexmedetomidine decreased haemodynamic indices of myocardial oxygen demand to a similar extent: esmolol decreased the rate-pressure product by 16 ± 3% and the pressure-work index (PWI) by 16 ± 3%, dexmedetomidine decreased the rate-pressure product by 26 ± 3% and the PWI by 16 ± 7%. However, these similar decreases resulted from different haemodynamic effects of the two study drugs. Dexmedetomidine had a more pronounced bradycardic effect than esmolol (P = 0.01) and increased systolic aortic pressure (SAP) by 15 ± 4% while esmolol decreased SAP by 8 ± 2% (P < 0.01). dP/dtmax and regional myocardial area decrease were lower after esmolol than after dexmedetomidine. Neither drug had an effect on myocardial oxygen consumption. Conclusions: Esmolol and dexmedetomidine decreased two haemodynamic indices of overall myocardial oxygen demand to a similar extent but neither drug decreased directly measured myocardial oxygen consumption in the territory of the left anterior descending artery.

Endotracheal Aspirate and Bronchoalveolar Lavage Fluid Analysis: Interchangeable Diagnostic Modalities in Suspected Ventilator-Associated Pneumonia?

ABSTRACT Authoritative guidelines state that the diagnosis of ventilator-associated pneumonia (VAP) can be established using either endotracheal aspirate (ETA) or bronchoalveolar lavage fluid (BALF) analysis, thereby suggesting that their results are considered to be in accordance. Therefore, the results of ETA Gram staining and semiquantitative cultures were compared to the results from a paired ETA-BALF analysis. Different thresholds for the positivity of ETAs were assessed. This was a prospective study of all patients who underwent bronchoalveolar lavage for suspected VAP in a 27-bed university intensive care unit during an 8-year period. VAP was diagnosed when ≥2% of the BALF cells contained intracellular organisms and/or when BALF quantitative culture revealed ≥104 CFU/ml of potentially pathogenic microorganisms. ETA Gram staining and semiquantitative cultures were compared to the results from paired BALF analysis by Cohens kappa coefficients. VAP was suspected in 311 patients and diagnosed in 122 (39%) patients. In 288 (93%) patients, the results from the ETA analysis were available for comparison. Depending on the threshold used and the diagnostic modality, VAP incidences varied from 15% to 68%. For the diagnosis of VAP, the most accurate threshold for positivity of ETA semiquantitative cultures was moderate or heavy growth, whereas the optimal threshold for BALF Gram staining was ≥1 microorganisms per high power field. The Cohens kappa coefficients were 0.22, 0.31, and 0.60 for ETA and paired BALF Gram stains, cultures, and BALF Gram stains, respectively. Since the ETA and BALF Gram stains and cultures agreed only fairly, they are probably not interchangeable for diagnosing VAP.